The Customer Premises Equipment (CPE), such as an Integrated Access Device (IAD) and an Analog Telephony Adapter (ATA), is relative to network-side equipment. It provides an interface for a communication terminal to communicate with a core network. In a home network, the IAD used at present accesses the core network by different means, such as Digital Subscriber Line (DSL), Asynchronous Transfer Mode (ATM), and Ethernet (ETH). The CPE faces the access network and provides the communication terminal with the functions such as the data service function and the Voice over Internet Protocol (VoIP) service function.
With the convergence of core networks, a terminal must support access to the core network through different edge networks. The IAD therefore also supports data and VoIP services in a radio way. A fixed access network has sufficient bandwidth and is capable of providing smooth paths for connected communication terminals. For a wireless network, however, bandwidth resources are precious. Even when a communication terminal is online, if the network detects that the terminal does not produce real Internet traffic, the network will disconnect the terminal actively. Therefore, the communication terminal must support the dial-on-demand function. In the prior art, dial-on-demand in a wireless network is mature for data applications. For VoIP services, however, no mature solution is available. The terminal that provides the VoIP service must send periodical registration update messages to a server to maintain the connection with the server in the radio access network, or else the server will determine that the VoIP device is unavailable. When originating a VoIP call, the communication terminal sets up a Packet Switched (PS) connection temporarily and initiates a re-registration process.
During the implementation of the present invention, the inventor finds at least the following problems in the prior art: (1) Because the setup of a radio bearer connection takes time, the call of the communication terminal may fail. (2) To guarantee success of the VoIP service, it is necessary to set up a connection with a wireless bearer via a data service, that is a network data domain, and then originate the call. This is too inconvenient for the communication terminal. Moreover, in the case of emergency calls, a user has no time to set up a wireless network connection, and therefore emergency calls are affected. (3) After the connection is disconnected due to dial-on-demand, the communication terminal fails to receive new calls. Because of such problems, in the operation of some wireless networks, dial-on-demand is always disabled when the VoIP service is enabled.